Project Summary Acute Kidney Injury (AKI) commonly occurs in critically ill patients in the ICU. Patients with severe AKI often require continuous renal replacement therapy (CRRT) because it enables hemodynamic stability and better volume control. Anticoagulation therapy is frequently used to keep the CRRT circuit (especially the blood filter) from clotting as many critically ill patients are prothrombotic, and/or when CRRT is commonly performed for multiple days. However both systemic heparin and regional citrate anticoagulation therapy are associated with higher costs, increased circuit complexity, and complications. Consequently a blood filter that operates clot free with little to no anticoagulation for extended periods will eliminate the costs, complexity, and complications of administering anticoagulation therapy, reduce blood loss, reduce the cost of CRRT due to filter clotting and replacement, and reduce the risk of not delivering an adequate dialytic dose to the critically ill AKI patient. We propose to develop an anticoagulant-free blood filter for extended extracorporeal applications using ultra-high- flux and blood compatible silicon nanopore membranes. In the Phase I SBIR project, we will characterize membrane clearance characteristics and optimize the blood flow path of the filter.